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Title: Nonlocal nucleon-nucleus interactions in (d,p) reactions : the role of the deuteron d-state
Author: Bailey, Gregory William
ISNI:       0000 0004 5992 3555
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2016
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Traditional (d,p) reaction models use local optical model potentials to represent the deuteron-target interaction. Within such models, the deuteron d-state contributes little to differential cross sections, as local potentials are only sensitive to low n-p relative momenta. However, recent work by Timofeyuk and Johnson, that includes the inherent nonlocality of the nucleon-target optical model potentials, suggests this is not true of nonlocal models which include deuteron breakup. This study showed that nonlocal deuteron-target potentials, found with a pure s-state deuteron, are influenced by large n-p relative momenta. The d-state can dominate the deuteron wavefunction at high momenta, suggesting d-state effects could be significant in nonlocal reaction calculations. This work incorporates the d-state into deuteron-target potentials, in the presence of nonlocal nucleon-target interactions and breakup. This is found using energy independent nonlocal nucleon-target optical model potentials of the Perey-Buck type. Deuteron channel distorted waves can then be found and used to calculate differential cross sections. The proton channel is constructed in the same manner. It is shown that the d-state effects from the central part of the deuteron-target potentials significantly alter calculated differential cross sections, when compared to nonlocal pure s-state calculations. The d-state also produces a tensor component of the deuteron-target potential, but this has negligible effects on cross section calculations. The choice of nucleon-nucleon potential, used to construct the deuteron wavefunction, is also investigated. It is shown that, within this works approach, calculated differential cross sections are sensitive to this choice. This is because the resulting wavefunctions have different high momentum behaviors. This sensitivity is shown to be enhanced if the final state of the transfered neutron has a large separation energy. This work concludes that in nonlocal (d,p) reaction models, which include break-up effects, the deuteron d-state gives a significant contribution to the deuteron-target potentials. The inclusion of nucleon-nucleus nonlocality in the deuteron-target potentials has produced sensitivity to the high momentum components of the deuteron wavefunction, where the d-state can dominate. The high momentum structure of the deuteron wavefunction differs between N-N models. As such, differential cross sections from this works approach can significantly change depending on the choice of deuteron wavefunction.
Supervisor: Tostevin, J. A. ; Timofeyuk, N. K. Sponsor: STFC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available